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January 2015

The History of Cats: Part I

A look back at the earliest machines used for slope grooming and the pioneers who invented them.
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In the modern ski industry, we take big, powerful snowcats with impressive features and implements for granted. But it was not always so! Groomers arrived well after resorts were launched and chairlifts began to climb our hills. They have come a long way in a short time.

Early ski area operators quickly realized that something had to be done about the bumpy and uneven surface caused by skier traffic. Then, too, if a heavy snowfall occurred, beginner and intermediate skiers floundered in deep powder. Resorts needed a way to create an enjoyable skiing surface. But it wasn’t until the 1960s that they began to adopt snowcat grooming technology.

In pre-cat days, ski area workers—especially patrollers—were assigned to ski-pack, boot-pack, or shovel-pack the trails. Squads would make their way up or down a trail to compress fresh snow. It was manifest from the start that this method was not feasible for regular grooming.

Recognizing the need for a mechanical solution, Winter Park manager Steve Bradley developed the first dedicated grooming implement. Taking his cue from road graders and land planers, Bradley created a fleet of “graders” to smooth the snow and remove bumps. Bradley cites this as a reason for his invention: “I was a damn good skier if I do say so myself, but I could not ski bumps!”

The Bradley Packer-Grader (XPG-1), first used in 1951, was a cumbersome yet exciting device: a rolling slatted drum, fitted in front with a 3” blade of steel cutting teeth to trim the tops of bumps. The blades were held by springs (screen door springs, to be exact), and could be raised and lowered by a reel system.

A metal frame encased the drum, with handles that the operator held as he skied in front. It need hardly be explained how dangerous (albeit fun) it was to operate the 400-pound machines. The operator “had only God to help him if the machine cut loose,” John Fry once wrote.

For its time, the Bradley Packer-Grader was a revolutionary tool. Bradley’s only lament was that it did a poor job of dressing the surface. Nevertheless, it was a step in the right direction.

Meanwhile, other ski area operators were trying to adapt farm and construction equipment to the purpose. A wide-track Oscar bulldozer was used, with varying results. But the pioneers quickly concluded that existing machinery was not sufficient.


Earlier still than these efforts, over-the-snow vehicles were employed in military, agricultural, and scientific fields where Arctic conditions required specialized transportation. As early as 1911, Wolseley Motor’s Caterpillar-tracked vehicles were employed on an Antarctic expedition. A Model T Ford was modified in 1913 with tracks in the rear and two skis in the front.

In 1922, Joseph Armand Bombardier, who tinkered with cars in his garage, built a propeller-drive snow vehicle. He spent more than 10 years refining the technical aspects of such vehicles.

Also developed in 1922, the Armstead Snow Vehicle was essentially a tractor that navigated snow by means of two rotating cylinders with helical flanges. Henry Ford is purported to have demonstrated it.

In 1936 Bombardier patented several key innovations that are still incorporated into snowcat design, including a rubber coated sprocket design, tracks with rubber belts, and a flexible suspension system. He began mass-producing his machines in 1937. Those patents expired in 1954, and were adopted by many other manufacturers.

At about the same time, Studebaker designed and manufactured the M29 Weasel, a tracked vehicle designed especially for use on snow in World War II.

In 1954, Swedish farm equipment engineer Lars Larsson, seeking a way to travel for his winter fishing trips, invented the Aktiv Snow Trac snowcat, a small machine manufactured between 1957 and 1981. This was the first snowcat to employ a wheel for steering rather than levers or sticks. The Snow Trac found its way into military locations and oil fields and was eventually adapted for ski area use. It was a viable competitor to Tucker (see below) for a time, with the Snow Master model even sighted at the 1972 Sapporo Olympic Games, sporting a very peculiar set of front and rear slatted rollers.

Speaking of Tucker: it is to this company that we owe the name “snowcat,” as its over-the-snow vehicle was (and is) named the “Sno-Cat.” First envisioned by E.M. Tucker Sr. in the early part of the 20th Century, the “Tucker Sno-Cat” company came into existence in 1942. Its initial models had augers, skis, and pontoons. Some were equipped with just two tracks, as opposed to the four-track design we now associate with Tucker.

Many early Sno-Cats were employed in the Arctic, but they found their way to winter resorts soon enough. They were the transit machine of choice in the 1950s and into the ’60s. Tucker Sno-Cats are still frequently seen in Nordic grooming operations, utility company transportation, search and rescue operations, mining, etc., though they are rarely spotted at ski resorts any more.


It is difficult to pinpoint when snowcats entered into mainstream grooming use—resorts worldwide were experimenting with them in the early 1960s. Winter Park was one; it used a Kristi Snowcat (another short-lived ’50s/’60s tracked snow vehicle) to pull a Bradley Packer from the top of the T-Bar to the point of descent. With various ski resorts using snowcats for personnel transport, the simple “track packing” effect of driving the vehicles around the mountain must have piqued interest in their potential for snow surface grooming.

In the Spring 1961 issue of Ski Business, Charlie Lord offered tips on trail grooming, codifying some of the earliest thoughts on the art of grooming. He suggested: "1. Roll your slopes after fresh snow falls. 2. During icy periods, break up hard surfaces with scratchers. 3. Eliminate booby traps such as deep ruts, over-large moguls or wind-drifts by machine grading or hand shoveling." His ideas, if not his methods, are still relevant to trail maintenance today.

That year also saw the advent of Bombardier’s Snow Packer, the first machine produced by the company with wide tracks and designed specifically for ski area grooming purposes. Only two were produced, one of them used by Mt. Orford Ski Centre in Quebec.

In Italy, Ernst Prinoth, a passionate racecar driver, produced his prototype snow groomer, the P60, in 1962, after two years of research and development. By 1964, Prinoth was mass-producing its next model, the P15. Like Bombardier, Prinoth got his start by working and experimenting in his garage.

It was in 1962, says Curt “Blademaster” Bender, veteran groomer and professor emeritus of Ski Area Operations at Colorado Mountain College, that the industry began to embrace slope grooming. A grooming expo was held at Aspen that year, with the Bradley Packer, a John Deere 1010 Dozer, and the Oscar bulldozer present and demonstrated in grooming applications. This expo was the impetus for ski area operators to begin taking the idea of grooming seriously.


As the idea of using snowcats for grooming caught on, attention turned to grooming implements. The earliest of these were quite crude (think chain-link fence, with some cinder blocks on it for weight, or bed springs or a series of chains used as drags). Still, they were revolutionary at the time, and definitively preferable to boot or shovel packing.

Marrying the concept of the Bradley Packer to the snowcat resulted in rolling-stock implements, such as the roller and the powder-maker. Rollers were cylindrical drums connected to a pintle hitch on the snowcat by a v-shaped steel frame reduced to a tongue and eye-hook. The roller was an excellent implement for use after a fresh snowfall, as it would compress the powder and leave a nice, smooth surface.

While some rollers were slat designs, most were made from corrugated culvert pipe. Thus, they provided skiers with their first taste of the corduroy pattern so lusted for still.

The roller, however, was not practical on hard or icy snow, as it would simply ride over it. On sidehills, the roller had a tendency to jackknife. Old-time groomers recall the challenge of trying to catch up to a roller as it passed by on the downhill side! (Not 24 hours before writing that line, I was making a sidehill turn myself, trying to keep a roller behind me after a big snowfall at Ski Cooper. The roller remains a useful tool under certain circumstances.)

The first rolling-stock solution for harder snow was the “Powder Maker,” developed by Otto Wallingford (who then founded Valley Engineering) in 1968. The Powder Maker combined the principle of the drag with that of the roller. Rather than a solid metal drum, the Powder Maker sported an expanded metal roller, which would scuff up the surface, leaving behind a fine particulate, or “powder.” Later versions of the Powder Maker were larger, and used three or five roller cages, which could be hydraulically angled to increase friction with the snow, effectively cutting through hard-pack.

Blades were another early addition. References to “snow plow” blades for snowcats are seen in advertisements as early as 1965. The first front blades were straight, with only the ability to raise and lower. Fixed U-blades came next, to keep snow within the blade.

While winch snowcats were still decades away, the earliest reported experiments with winching appeared in the October 1967 Ski Area News, which cites a system developed by Ray Parker of "one bulldozer anchoring the other and hauling it back on a winch. Working in tandem this way, [one] can safely cut trails up to a 70 percent gradient."

Many early snowcat operators were legendary individuals themselves. Bender recalls working with a Vietnam veteran fighter pilot, “Jock,” who “drove his cat like an F-14.” He worked at Taos for a supervisor known as “Cat Daddy.”

In those pre-winch days, it was not uncommon for groomers to experiment with techniques for grooming the steepest and gnarliest trails once they had finished surfacing the gentler terrain. And in those days, the operators had the support of their supervisors and managers for such adventures.

This was the era of “cowboy grooming.” The science had not been fully studied, and the constituent art not yet perfected. Many of today’s groomers, in Recaro seats with tunes blasting, crawling up a 40-degree pitch with the help of a winch and pulling a tiller, cannot comprehend either the challenges or the excitement of those days!


In the late ’60s and early ’70s, more snowcat innovations—and brands—began to appear. PistenBully got its start after founder Karl Kässbohrer, CEO of the Kässbohrer Bus Company, took a skiing vacation in South Tyrol in 1967. Inspired to create a machine to groom the slopes, he began work on a prototype, “Special Vehicle 001,” in December 1968. By the next month, the PistenBully name was adopted. With Walter Haug’s direction, the design was improved to incorporate an 80hp Daimler-Benz engine, hydrostatic pumps and motors, and a host of other forward-thinking ideas. Further testing and tweaking resulted in the diesel-powered, hydrostatic-driven, aluminum-tracked PB145, which was imported into the U.S. by Valley Engineering.

In 1976, PistenBully’s PB170D introduced major advancements, including electronic steering controls, frame improvements for front blades, and creature comforts in the cabin based on Kässbohrer’s Setra bus interiors.

Thiokol, a Utah-based chemical company, produced snowcats fitted with front blades and culvert rollers until 1978, when John DeLorean (yes, that John DeLorean) purchased its snowcat division. Several Thiokol machines saw extensive use in the ski industry, most notably the Spryte, the 2100 Packmaster—a workhorse grooming snowcat often seen pulling a Trail Grader (a 5th-wheel hitch roller and blade) or equipped with a compactor bar—and of course, the 3700 Hydromaster with an Allis Chalmers diesel engine, hydrostatic steering, 6-way hydraulics to the front, and 4-way hydraulics to the rear, introduced in 1976. This was the predecessor to the revered LMC 3700.

Throughout the 1970s, Bombardier produced a successful line of “Skidozers.” In 1979, the SV302HD with hydrostatic controls hit the market.

With the number and variety of machines expanding, the 1972 NSAA meeting at Waterville Valley, N.H., featured a contest to compare them. “Tucker won first for mogul planing and dressing with the Tucker with Mogul Planer; the Thiokol 2100 V-8 with Mogul Planer took second and the Thiokol 2100 6 Blade and Dresser Bar took third...Thiokol hard snow preparation with the Thiokol 2100 V-8 12-foot powdermaker followed by the Tucker V-8 Catamount and the Bombardier 501 12-foot powdermaker... Bombardier's Skidozer 501 was named the best overall vehicle at the show." (SAM, Spring 1972).

Today’s implement of choice—the power tiller—first appeared in 1968 with Jim Kelly’s invention of the “Hard Pack Pulverizer.” Prinoth also lays claim to inventing the power tiller, citing its implement developed in Italy in 1973. In the Fall 1975 SAM, a West Mountain ad speaks of a Sno-Tiller, an "aggressive high-speed hardpack breaker... conditions thick, uniform layer of chips ready for additional surface powdering." In 1977, PistenBully introduced its hydrostatic power tiller. In all, the power tiller introduced a new level of snow processing, and launched the modern era of grooming.

It also launched a new series of challenges. Dan Torsell (my father and industry veteran) recalls the excitement of demoing a power tiller on a Thiokol Hydromaster 3700 circa 1981; his area had been using older machines and rolling stock. The GM was first to try the machine, and he took Dan with him. After a few beautiful passes in the beginner area, he cut through the trees on a cat road to an adjacent trail. Dan recalls, “All of a sudden there was a bang and a jerk. We looked back, and there was the tiller, snapped off from one side! We never had trouble fitting the Tucker or the 145 through those trees.”

The second part of this history (March 2015) will recount how grooming technologies and practices have evolved to the present.